Introduction: This pilot project proposes a novel integration of two existing simulation technologies in order to model, analyze and measure treatment for diabetic retinopathy (DR) in the population served by the St. Louis VA Medical Center (St. Louis VAMC). Specifically, to use agent-based modeling to simulate the population, and discrete event simulation to model the eye clinic. The purpose of this hybrid simulation is to enable a new type of measurement of clinical services. Changes to the Medical Center capacity, flow, size or policy will be measurable at the level of the population health, on the rate of DR progression in the population. Conversely, changes in the population epidemiology or demography may be measured at the level of demand for access to clinical services. Aims: This project will have two fundamental aims: (1) to build a simulated cohort of diabetic patients which mirrors in all relevant respects the population of diabetic patients seeking treatment or surveillance for DR at St. Louis VAMC; and (2) to implement this population in combination with a discrete event simulation representing the St. Louis VAMC eye clinic in order to project how demand for service, and DR progression in the population, will evolve over the next ten years. Methods: The cohort will be mined for relevant covariates for DR, which will be implemented in an accelerated failure time model for DR progression, and integrated into a statechart model of DR for the agent based population. This population will be married to the simulated clinic, where individual agents seek treatment and care for DR according to standard processes extant in the St. Louis VAMC eye clinic. Projections of demand for service over the next ten year based on population wide improvements in Body Mass Index and Hemoglobin HbA1c will be measured, as well as projections of access to care based on potential reductions in screening for background DR based on recommendations from the literature on DR. Implementation: The prospective PI has established ties with the Acting Chief of Ophthalmology at St. Louis VAMC, and the prospective Co-Investigator is a practicing ophthalmologist in the eye clinic. Results from the pilot study will be readily adoptable at the local level, and may be disseminated throughout VA in part through the VA Innovations Program, and through traditional channels for reporting successful research. Additionally, it is the intention of the investigators to advance this project through further Merit Review application upon completion of this pilot.